Pressure Sensitive Adhesives Based on Epoxidized Soybean Oil: Correlation Between Curing Conditions and Rheological Properties

Abstract

Renewable resources, including vegetable oils, can be used as feedstock for the manufacture of pressure sensitive adhesives (PSA) that can compete with those derived from petrochemical sources, but with the environmental benefit of being sustainable. Completely bio-based PSA with tunable viscoelastic properties were synthesized from mixtures of epoxidized soybean oil and sebacic acid by a solvent-free one-step reaction, in the absence of catalyst. Curing conditions and pot-life were determined for formulations with stoichiometric acid/epoxy ratio. Curing time ranged from the gel point (t gel ) to t gel + 30 min at the selected temperature (170 C) to study the correlation between the reaction, rheological behavior, and potential adhesive performance. These renewable PSA can be tailored by controlling the curing parameters according to the desired application, since the rheological profile and gel content were greatly dependent on the curing conditions. In particular, the obtained adhesives cured at 170 C between 65 and 75 min showed the best balance between tack and cohesion.Keywords Sebacic acid Á Renewable Á Bio-based Á Dicarboxylic acids Á Viscoelastic properties J Am Oil Chem Soc (2018) 95: 525-532.

Enhanced Adhesion and Cohesion of Bioinspired Dry/Wet Pressure-Sensitive Adhesives

“…PSA performance was measured against both stainless steel and high-density polyethylene (HDPE) test substrates. First, we evaluated PSA shear strength, which is related mostly to the cohesive strength and resistance of the adhesive to flow under shear (Figure B) . As compared to other types of adhesives such as structural adhesives, PSAs generally experience viscous flow, resulting in very low shear strength when the evaluation is performed using conventional lap shear tests .…”

“…First, we evaluated PSA shear strength, which is related mostly to the cohesive strength and resistance of the adhesive to flow under shear (Figure 3B). 61 As compared to other types of adhesives such as structural adhesives, PSAs generally experience viscous flow, resulting in very low shear strength when the evaluation is performed using conventional lap shear tests. 1 Nevertheless, in-service PSAs tapes are often expected to persist for long periods of time under constant shear stress; thus, the PSA industry uses static shear tests (constant load creep test) for determining the shear failure time as measure of the cohesive strength or shear holding power of PSAs.…”

Epoxidation Reaction of Soybean Oil: Experimental Study and Comprehensive Kinetic Modeling

“…4,5 In addition to the main studies involving ESO as a plasticizer for PVC, several interesting applications of ESO have been developed. Some examples have been highlighted: Kong et al 7 verified the viability of using the ESO as a plasticizer for poly(latic acid) (PLA), in addition to a synergistic effect with a functional eggshell as a nucleating agent; Ciannamea and Ruseckaite 8 and Lee et al 9 studied the use of ESO as a pressure-sensitive adhesive, after a curing process; Xu et al 10 developed cellulose aerogels with grafted ESO, aiming at the absorption of oil from oil spills in the ocean.…”

UV-Curable Bio-Based Pressure-Sensitive Adhesives: Tuning the Properties by Incorporating Liquid-Phase Alkali Lignin-Acrylates

“…For a good-performing PSA, the bonding frequency range is associated with a low bonding plateau modulus and the debonding frequency corresponds to high dissipation energy. 51 The two moduli increase with frequency, attaining a maximum storage modulus that meets the Dahlquist criterion, which states the need of a PSA to have a plateau modulus less than 10 5 Pa, so as to wet a rough surface, which later on forms an excellent bond under a mild pressure. The viscoelastic behavior depends on the frequency, exhibiting an elastic behavior (G′ > G″) at low frequencies and a viscous behavior at high frequencies, unless crossover took place at a much higher frequency.…”

“…The lower value of G″ relative to G′ indicates that crack propagation becomes less dissipative and fibrillation is minimized, revealing its good performance as a removable PSA, which is noticed in 10−20% LA. 51 Both 10 and 20% PSAs show a crossover near ∼10 rad/s. On the contrary, in the case of 30% LA, the loss modulus is greater than the storage modulus over the entire frequency range (G″ > G′) and no crossover is noticed because of the relatively lower cross-linking and aggregation.…”